Coil tubing services can be used instead of expensive workover rigs for efficiently and economicaly performing a wide variety of production, completion and workover problems in producing oil and/or gas wells or injection wells. Coil tubing services reduce well down time and, reduce costs, by performing many types of operations, and can perform the operations without killing the well. Coil tubing operations are performed by inserting a flexible tubing, which is normally coiled on a reel, into a well conduit and fluids are inserted into the coil tubing under pressure to perform various mechanical and chemical functions. For example, a well conduit may be washed, coated with corrosion inhibitors, coated with a protective film for increasing the life of the well conduit instead of replacing it, removing paraffin with chemicals, perform acid treatments and many other operations.
However, in treating and/or coating well conduits in the past, it has been difficult to obtain an even and complete contact of the interior of the well conduit with the injected fluids. First, the hydrostatic head of the fluids in the coil tubing diminishes the ability to accurately control the volume of the injected fluids at the desired locations. Secondly, the present systems do not insure a thorough circumferential coating of the well conduit with the injected fluids.
The present invention is directed to a method and apparatus of injecting fluid into a well conduit by coil tubing which overcomes the problems of the prior art by providing a complete and controlled contact of the interior of the well conduit with the injecting fluid.